Arc chute providing barriers parallel to the direction of contact separation



Oct. 25, 1955 E. w. BOEHNE 2,721,916

ARC CHUTE PROVIDING BARRIERS PARALLEL TO THE DIRECTION OF CONTACT SEPARATION Filed Aug. 5, 1952 2 Sheets-Sheet 1 Hil & 0&0 0&0 00 ogo $51 .2

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ARC CHUTE PROVIDING BARRIERS PARALLEL TO THE DIRECTION OF CONTACT SEPARATION Filed Aug. 5, 1952 2 Sheets-Sheet 2 g IMF/32 M/m United States Patent Ofiice 2,721,916 Patented Oct. 25, 1955 ARC CHUTE PROVIDING BARRIERS PARALLEL TO THE DIRECTIDN OF CONTACT SEPARATION Eugene W. Boehue, Wellesley Hills, Mass., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application August 5, 1952, Serial No. 302,791

Claims. (Cl. 200-144) This invention relates to circuit interrupting devices and more particularly to are extinguishing means for use in connection therewith.

In the construction and operation of alternating current circuit interrupters, it is frequently necessary to provide means for extinguishing quickly the are which is drawn between separable arcing contacts. This arc is usually blown by blowout means, such as a magnetic blowout coil or an air blast into an arc chute which is arranged to quench the are by lengthening it, cooling it, or a combination of both.

Arc chutes having spaced insulating plates to lengthen and squeeze the are into narrow slots have been used to rapidly increase the arc voltage, decrease the arc current and improve the power factor, thereby facilitating interruption of the are at a current zero. However, it has been found in many cases that the arc voltage developed by the arc chute was not the most favorable for interrupting the power circuit.

The geometry of the arc chute is an important factor in determining the arc voltage which will be developed for circuit interrupting purposes. This are voltage can be expressed as a percentage of the line voltage and therefore is not limited to any particular voltage class of breaker.

Therefore, in accordance with the invention claimed, an arc chute having a predetermined geometrical configuration is provided adjacent a pair of arcing contacts for receiving the are at one end thereof and exhausting the deionized arcing products at the other end thereof. The are chute employs an arc extinguishing device comprising a pair of side walls and a plurality of groups of perforated barrier plates arranged between the side walls in groups. Each barrier plate of each group extends in one direction substantially parallel with the direction of contact separation and extends in another direction substantially longitudinally of the axis of the arc chute. The groups along their longitudinal aXes are out of registry, that is, they are alternatingly angularly displaced so that the are upon entering the stack of barrier plates is compelled to assume a wave or zigzag shape as it passes through the arc chute.

It is, therefore, one object of the present invention to provide a new and improved arc interrupting device in which the arc is constricted in a predetermined manner as it passes through an arc chute.

Another object of this invention is to provide a new and improved arc extinguishing device in which the arc is divided into parallel arc sections.

A further object of this invention is to provide an arc chute structure which controls the arc current and are voltage to rapidly interrupt the arc in a manner heretofore predicted from fundamental considerations.

, Objects and advantages other than those above set forth will be apparent from the following description, when read in connection with the accompanying drawing, in which:

Fig. 1 is a view in cross section of a magnetic blowout type circuit breaker employing the present invention;

Fig. 2 is an enlarged side view of the barrier plate assembly with the arc chute side wall removed;

Fig. 3 is an enlarged plan view of the arc chute shown in Fig. 1;

Fig. 4 is an enlarged end view of the arc chute shown in Fig. 2;

Fig. 5 is an enlarged end view of a modification of the arc chute barrier plate assembly shown in Figs. 1 to 4;

Fig. 6 is a side view of a modification of the barrier plate assembly shown in Fig. 2;

Fig. 7 is an enlarged plan view of the arc chute embodying the barrier plate assembly shown in Fig. 6;

Fig. 8 is an end view of the arc chute shown in Fig. 6;

Fig. 9 is another modification of the barrier plate assembly shown in Fig. 2;

Fig. 10 is an enlarged plan view of the arc chute embodying the barrier plate assembly shown in Fig. 9; and

Fig. 11 is an end view of the arc chute shown in Fig. 9.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a magnetic blowout type of circuit breaker including as elements thereof a pair of terminal studs 6 and 7 for connecting the circuit breaker to line conductors (not shown). Although in general, circuit breakers of the type considered in Fig. 1 are provided with a plurality of similar pole structures, one for each phase of a polyphase electric circuit, only one such pole structure is shown in the drawing and the circuit breaker will be described in detail as if it was of the single pole unit type.

The circuit interrupter or breaker in Fig. 1 comprises essentially means for opening the circuit to form the interrupting arc and an arc extinguishing structure. Specifically, the circuit opening means comprises fixed current carrying contact 8 and tertiary contact 9, a fixed arcing contact 10, and a movable arcing contact 11. Arcing contact 11 is mounted on a lever 28 which is pivotally mounted at 12 on an extension 13 of the circuit breaker stud 6 and is operated by means of a reciprocally movable rod 14. The operating rod 14 is suitably connected to an actuating mechanism (not shown) for operating the movable contact between closed and open circuit positions. Fig. 1 illustrates the movable contact 11 in an intermediate position. The arcing contacts are electrically connected to the lower ends of terminal studs 6 and 7. Accordingly, when the breaker is connected in series in a power circuit and the arcing contacts are separated, an arc may form across the gap indicated.

For interrupting this power arc, an arc extinguishing structure, such as an arc chute 15 may be mounted so as to receive the power are which is under the influence of a magnetic blowout means. The are chute preferably is disposed directly above the arcing contacts, as shown, when the blowout means act upward, but may be mounted in any other suitable location when the blowout means act in other directions. The switch or arcing contacts and the magnetic blowout structure can assume any preferred form so that a brief description thereof will be sufiicient. The magnetic blowout means may comprise a core 17, poles 18, and a coil 16 which is electrically connected to the terminal stud 7 and to a metallic arc runner 19 so that the arc current (as the arc travels along the runner) flows through the blowout coil in a manner well known in the art.

Normally the current is carried in the closed circuit position of the breaker by contact 11 and the spring biased contact 8. While the movable arcing contact 11 is actuated to the open circuit position, current is shunted from fixed contact 8 first to fixed contact 9 and then to fixed arcing contact 10. As the arc is drawn by the movable arcing contact 11, the arc terminal on arcing contact 1%) is transferred to are runner 19, which is usually an extension arm of the fixed arcing contact 10. While the movable arcing contact 11 approaches its full opening stroke, the other are terminal transfers from the movable arcing contact 11 to an arc runner 20 which directs the are into the arc chute 15. One end of the blowout coil 16 is connected to the arcing contact and the other end to tertiary contact 9. When .the movable arcing contact 11 parts from contact 9 the flow of current is transferred from contact 9 to contact 16 through the blowout coil 1d. The movable arcing contact 11 subsequently parts from contact 3% to draw an arc. Accordingly, the blowout coil is already energized at the inception of the arc interruption to influence the arc in a well known manner, i. e. to drive it into the arc chute in an expanding loop. It will be apparent to one skilled in the art that the blowout field can be utilized in the most eihcient manner by disposing the iron poles 18 so as to cooperate with the blowout coil in the conventional manner outside of the arc chute.

In accordance with the invention claimed, are chute 15 is provided with side walls 23 and '24 and with a plurality of groups or sets of perforated spaced insulating barrier plates 25. Each group or set is arranged in a stack between the side walls 23 and 24 to extend in one direction substantially parallel to the direction of contact separation and is fastened to the side walls by means of insulated bolts 21. The groups along their longitudinal axes are arranged out of registry, that is, adjacent groups are angularly displaced with respect to each other so that the arc in passing through the stack of barrier plates is compelled to assume a wave or zigzag shape. As shown in Figs. 1 to 4, adjacent barrier plate groups are angularly displaced in opposite directions with respect to the longitudinal axis of the chute. The barrier plates divide the are into a plurality of parallel arc sections within the interplate gaps formed between adjacent barrier plates. These interplate gaps form a plurality of auxiliary arc passages. The apertures 22 of the plates of any group may be in alignment with each other or may be staggered in the difierent plates.

In Figs. 1 to 4, the groups of perforated barrier plates are arranged in staggered stacks between the side walls 23 and 24 to extend in one duection substantially parallel to the direction of contact separation. In the groups of barrier plates which are angularly displaced alternately in one direction and in another direction with respect to the longitudinal axis of the arc chute, any one group of plates is at its upstream end spaced narrowly with respect to one side wall and widely with respect to the opposite side wall and is at its downstream end spaced widely with respect to the above mentioned one side wall and narrowly with respect to the above mentioned opposite side wall. The upstream ends of the barrier plates are arranged in even and odd rows disposed side by side and all substantially parallel to the direction of contact separation and the downstream ends of the barrier plates are also arranged in such odd and even rows. The barrier plates in the upstream even rows terminate in the downstream odd rows and the barrier plates in the upstream odd rows terminate in the downstream even rows.

Fig. 5 shows another way of assembling the barrier plates illustrated in Figs. 2, 3 and 4. In an arc chute structure of the type shown in Fig. 5, the arc is gradually constricted as it passes from the upstream to the downstream ends of the arc chute.

As shown in Fig. 8 the groups of plates of Figs. 6 and 7 are so staggered that the upstream ends of the perforated barrier plates 25 are arranged in a predetermined number of rows and the downstream ends of barrier plates 25 are arranged to terminate in twice the number of upstream rows.

Fig. 8 shows in profile the geometric configuration oi the barrier plates having their upstream ends in a given upstream row and angularly displaced with respect to the longitudinal axis of the chute so that they terminate in the downstream end of the arc chute in rows which are arranged between the rows of the downstream ends of adjacent groups or sets.

The distinction between Figs. 3 and 4 on the one hand, and Figs. 7 and 8 on the other, is essentially that of degree and location of arc constriction.

In the structure of Figs. 3 and 4 there is a higher degree of constriction at the upstream end of the arc chute, a lower degree intermediately and, again a higher degree at the downstream end. This higher degree of constriction at the upstream end tends to retard entrance of the are into the chute because of the abruptness with which its constricting effect is imposed upon the arc.

In the structure of Figs. 7 and 8, on the other hand, the degree of constriction at the upstream end is lower and that in the intermediate portion of the chute higher. Hence, although the maximum degree of constriction may be less in this structure, the overall efiectiveness of its geometry may be greater.

In Figs. 9 to 11 the arc chute structure comprises perforated barrier plates 30 which are arranged in one direction substantially parallel to the direction of contact separation and in the other direction substantially longitudinally of the axis of the arc chute. The barrier plates are arranged in staggered groups or sets which form.

stacks of barrier plates arranged between the side walls 23 and 24 of the arc chute 15. Adjacent stacks are so arranged that the barrier plate sides 31 extend within theinterbarrier plate gaps of adjacent barrier plate groups. These overlapping barrier plates 30 are not intended to form angularly displaced stacks, i. e., stacks as shown in Figs. 1 to 8 in which one group of barrier plates is tilted toward the left and the adjacent groups are tilted toward the right of the arc chute 15.

Under normal interrupting conditions an arc is initiated immediately upon separation of the arcing contacts 10 and 11. The terminal of the are on fixed arcing contact 10 is driven over are runner 19 by the magnetic blowout means and the thermal effect of the arc. Before the movable arcing contact 11 nears its fully open position, the other terminal of the arc is moved from contact 11 to are runner 20 and is also driven by the blowout means and the thermal efiect of the arc toward the exhaust end of arc chute 15.

As the arc terminals move along the arc runners 19 and 29 toward the exhaust end of the arc chute, the arc is driven into the interbarrier plate gap.

In the arc chutes shown in Figs. 1 to 8, the arc rises into the barrier plate structure of the arc chute 15 under the influence of the blowout means and the thermal effect of the arc. The barrier plate structure divides the are into a plurality of parallel arc sections which extend within adjacent interbarrier plate gaps between the arc runners l9 and 20. The barrier plates are provided with transverse perforations which tend to permit a uniform distribution of gases in the interplate gaps. The perforations in the barrier plates permit the arc to extend from one side of each stack forming plate to the other. An are thus threaded through holes and stretched along cold ceramic surfaces tends to have a high voltage gradient or resistance.

The are rises in the interbarrier plate gaps under the influence of the blowout means and the thermal effect of the arc until it is constricted by the alternatingly angularly displaced barrier plates. As shown in Figs. 1 to 8, the arc can enter at the bottom of the arc chute 15 into the interbarrier plate spaces formed between ad acent barrier plates, and as it rises toward the exhaust ends of the stacks of barrier plates it is compelled to assume a wave or zigzag shape. The are is also constricted or squeezed by the edges of adjacent angularly dis-placed groups of barrier plates which tends to increase the arc voltage thereby aiding arc extinction. This type of arc chute structure subdivides the are into a plurality of parallel unstable arc branches and then exposes each arc branch to the action of particularly large cooling and deionizing surfaces to rapidly cool, elongate, and extinguish the arc.

Figs. 9 to 11 illustrate another way of forming a zigzag arc path which exposes the arc to the surface action of a great many barrier plates by arranging the barrier plate groups out of registry.

Although but a few embodiments of the present invention have been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an are between said contact, and an arc chute for receiving and extinguishing the arc, said chute comprising a plurality of staggered groups of spaced insulating barrier plates extending in the direction of contact separation so as to define a plurality of paths having a zigzag shaped cross section for dividing the arc into a plurality of parallel arc sections within the interplate gaps formed between said barrier plates.

2. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an arc between said contacts, and an arc chute for receiving and extinguishing the are, said chute comprising a pair of ide Walls and a plurality of groups of spaced barrier plates, each group arranged in a stack between said walls to extend in one direction substantially parallel to the direction of contact separation, said groups being angularly displaced along the longitudinal axis of said chute to provide zigzag arc paths.

3. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an are between said contacts, and an arc chute for receiving and extinguishing the arc, said chute comprising a pair of side walls and a plurality of groups of spaced barrier plates, each group arran ed in a stack between said walls to extend in one direction substantially parallel to the direction of contact separation, adjacent said groups being angularly displaced in opposite directions with respect to the longitudinal axis of said chute to provide zigzag arc paths.

4. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an are between said contacts, and an arc chute for receiving and extinguishing the arc, said chute comprising a pair of side walls and a plurality of groups of spaced barrier plates, each said group arranged in a stack between said walls to extend in one direction substantially parallel to the direction of contact separation, adjacent said groups being angularly displaced in opposite directions with respect to the longitudinal axis of said chute with the upstream ends or" said barrier plates arranged in even and odd rows disposed side by side and all substantially parallel to the direction of contact separation and the downstream ends of said barrier plates in such even and odd rows, said barrier plates in said upstream even rows terminating in said downstream odd rows.

5. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an are between said contacts and an arc chute for receiving and extinguishing the arc, said chute comprising a pair of side walls and a plurality of groups of spaced barrier plates, each group arranged in a stack between said walls to extend in one direction substantially parallel to the direction of contact separation, adjacent said groups being angularly displaced in opposite directions with respect to the longitudinal axis of said chute with the upstream end of said barrier plates arranged in even and odd rows disposed side by side and all substantially parallel to the direction of contact separation and the downstream end of said barrier plates in such even and odd rows, said barrier plates in said upstream even rows terminating in said downstream odd rows and said barrier plates in said upstream odd rows terminating in said downstream even rows.

6. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an are between said contacts, and an arc chute for receiving and extinguishing the are, said chute comprising a pair of side walls and a plurality of groups of spaced barrier plate each group arranged in a stack between said walls to extend in one direction substantially parallel to the direction of contact separation, said groups being angularly displaced in opposite directions with respect to the longitudinal axis of said chute with the upstream end of said barrier plates arranged in a predetermined number rows disposed side by side and all substantially parallel to the direction of contact separation and the downstream end of said barrier plates terminating in twice the number of said upstream rows.

7. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an are between said contacts, and an arc chute for receiving and extinguishing the are, said chute comprising a plurality of staggered groups of spaced barrier plates arranged in stacks and extending in the direction of contact separation for dividing the are into a plurality of parallel arc sections within the interplate gaps formed between said barrier plates, said stacks being arranged so that the barrier plates of one group overlap the barrier plates of adjacent groups to pinch the are between the overlapping portions of said barrier plates.

8. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an arc between said contacts, and an arc chute for receiving and extinguishing the are, said chute comprising a plurality of staggered groups of spaced perforated barrier plates arranged in stacks and extending in the direction of contact separation for dividing the arc into a plurality of parallel arc sections within the interplate gaps formed between said barrier plates, said stacks being arranged so that the barrier plates of one group extend within the interbarrier plate gaps of adjacent groups.

9. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an arc between said contacts, and an arc chute for receiving and extinguishing the arc, said chute comprising a plurality of groups of spaced perforated barrier plates arranged in stacks and extending in the direction of contact separation for dividing the arc into a plurality of parallel arc sections within the interplate gaps formed between said barrier plates, said groups of plates being angularly disposed about an axis parallel to the direction of contact separation.

10. An electric circuit interrupter comprising a pair of separable arcing contacts, means for drawing an arc between said contacts, and an arc chute for receiving and extinguishing the are, said chute comprising a plurality of groups of parallelly arranged spaced barrier plates with each plate extending in the direction of contact separation, adjacent ones of said groups being angularly disposed about an axis parallel to the direction of contact separation for providing a plurality of arc passages between said barrier plates.

References (Iited in the file of this patent UNITED STATES PATENTS 2,258,150 Scott, Jr. Oct. 7, 1941 2,460,727 Atwood et al. Feb. 1, 1949 FOREIGN PATENTS 403,068 Germany Sept. 26, 1924 873,615 France Mar. 30, 1942 

